Flashbacks, reunions, and executions will be the order of the day when “Hawaii Five-0” airs its 150th episode. 

Wo Fat is dead and gone, but his story is far from over. Yao Fat/Dae Won (George Cheung), the father of McGarrett’s (Alex O’Loughlin) most notorious enemy, summoned the Five-0 leader to his prison last season.

Steve won’t be the only McGarrett to visit the aged criminal, however. Doris (Christine Lahti), MIA since season 3, will drop by Yao Fat’s haunt as “Ka makuahine a me ke keikikane (Mother and Son)” begins.

What's In Store For "Hawaii Five-0"'s 150th Episode?

“Five-0 must free McGarrett’s mother, Doris, when Catherine (Michelle Borth) informs them that she was captured and is about to be executed after attempting to free Wo Fat’s imprisoned father,” CBS teased.

“Also, Chin loses his appeal to have Sara’s adoption delayed, and she must move to Mexico, on the 150th episode of ‘Hawaii Five-0.’” 

The situation in the present is dire, but “Five-0” will make time for a few flashbacks. As Steve fight’s for his mother’s life and works to unspool the mystery surrounding Yao Fat. Viewers can expect toe see a young Doris (played by Emma Schlamme) as well as a 10-year-old McGarrett (played by Nicolai Makana Perez) and a 15-year-old McGarrett (played by Jacob Miller).

"It's really a mythology episode," showrunner Peter Lenkov told TVLine. "It will tie up some loose ends and spark a new storyline in the episode that follows."

Will McRollins Reunite?

With all that’s going on, viewers shouldn’t expect Rollins and McGarrett to rekindle their relationship. In fact, photos indicate that Steve and Lynn (Sarah Carter) will share a kiss upon the latter’s return.

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It’s been a long time coming, but it seems the members of the McRollins ’ship have finally realized they are just not meant to be. 

"People are interpreting it like her coming back into the relationship and starting all over again, but I just don't think that can happen after all that these two have gone through," Lenkov told Entertainment Weekly. "Her relation to the story is more plot-driven than reigniting that relationship."

The 150th episode will air on Nov. 4. In the meantime, catch the “Hawaii Five-0” Halloween episode tonight at 9 p.m. ET on CBS. Click the video below to see a preview.